The aim of these studies is to provide detailed understanding of the mechanisms which control the rate of hemoglobin synthesis in the maturing mammalian erythroid cell. Emphasis will be placed on elucidating the non-messenger RNA factors which moderate the rate of protein synthesis and which influence the type of protein synthesized. Studies in both animal and human erythroid cells and reticulocyte cell free systems will specifically study the roles of ribosomal proteins, cellular environmental factors, hemoglobin and globin polypeptide subunits and the external cell membrane in changing the rates and proportions of specific proteins synthesized. A study will be made of the role of the erythroid cell membrane in moderating the rate of protein synthesis in the cell. In particular, the role of unbalanced chain synthesis on cell membrane function will be investigated.